1. Field of the Invention
This invention relates to recording apparatuses and, more particularly, to a recording apparatus for recording a tracking-control pilot signal and an information signal in a time-divisionally multiplexed manner.
2. Description of the Related Art
As one of the information recording apparatuses of this kind, there been known a digital type magnetic recording apparatus.
To allow tracking of the rotary head to be carried out at the time of reproduction, the prior known digital type magnetic recording and reproducing apparatus employs one of the following exemplary methods:
(i) A tracking-control pilot signal is recorded in an area provided in a portion on each helical track in a time-divisionally multiplexed manner with an information signal (the area division pilot method) as is used in a DAT (Digital Audio Tape recorder); PA1 (ii) A tracking-control pilot signal of low frequency is recorded in a frequency-multiplexed manner (the frequency multiplex pilot method) as is adopted in an 8 mm VTR; and PA1 (iii) The head is made to oscillate by using a movable element such as a dimorph and this oscillation brings out change of the reproduced envelope, from which the tracking-control state is detected (the dither method).
The above-described conventional methods on consideration of affording an improvement of the record density, have, however, the following drawbacks:
(i) In the so-called area division pilot method used in the DAT (Digital Audio Tape recorder), etc., because part of the track is occupied only by the pilot signal, the redundancy of information as a whole increases. Also, because what is permitted for use in detecting the tracking state is limited to only that part of the track, there is another drawback in that the curvature of the track cannot be detected.
(ii) In the frequency multiplex pilot method used in the 8 mm VTR, it is not only difficult to enhance the SN ratio of the pilot signal but the method also increases the error rate of digital information because the extra signal of the low frequency is multiplexed with the information signal. Also, a modulation method that suppresses the low-frequency component has, therefore, to be employed in combination with a filter for the separation processing. Hence, there is a drawback in that the modulation method of large redundancy such as the frequency-modulation method or the so-called 8-10 conversion processing means must be adopted.
(iii) In the so-called dither method that oscillates the head, the introduction of the variation of the envelope causes the reproduced output to decrease. Another drawback is that the reproduced signal suffers waveform distortion and jitter resulting from the amplitude variation.